Compound gas turbine plant, including simplified ducting arrangements



June 1956 J. BARRETT ETAL 2,750,738

COMPOUND GAS TURBINE PLANT, INCLUDING SIMPLIFIED DUCTING ARRANGEMENTS Filed Aug. 22, 1952 A L TGENA T02 /A/TEK COoL g Invent-or John L.Barrett Lerzy A.L.Latoszynski Clifford Morris Adolf Frankel 'Zfformy;

United States Patent COMPOUND GAS TURBINE PLANT, INCLUDING SHVIPLIFED DUCTING ARRANGEMENTS John Leslie Barrett, Jerzy Andrzej Leslaw Latoszynski, Cliflord Morris, and Adolf Frankel, Rugby, England, assignors to The English Electric Company Limited, London, England, a British company Application August 22, 1952, Serial No. 395,894

Claims priority, application Great Britain September 4, 1951 Claims. (Cl. 60-39.15)

The invention relates to a compound gas turbine plant having high pressure and low pressure compressors, and high pressure and low pressure turbines, the high pressure turbines driving the high pressure compressors, and using two low pressure turbines in parallel flow connection, one of said low pressure turbines driving the low pressure air compressor and the other providing the useful power output of the plant. In gas turbines of this type it has hitherto been necessary to employ a considerable amount of ducting to carry the air and gas to and from and between the various units of the installation such as the compressor, inter-cooler, combustion chamber(s), high pressure and low pressure turbines. Much of this ducting has to be designed to carry gas at a relatively high temperature, which requires provision to be made to allow for considerable thermal expansion to take place in its length. The number of bends necessary in the ducting has also given rise to a considerable amount of pressure drop and has been a source of power loss.

It is an object of the present invention so to arrange the individual items in the installation as to reduce both the length of ducting and the number of bends in it, thus tending to improve the appearance of the plant, reduce its overall size, eflect a saving in first cost and increase its efficiency.

Plants constructed in accordance with this invention are characterized by the provision of two high pressure compressors in parallel flow connection, driven respectively by two high pressure turbines also in parallel flow connection, one of said high pressure turbines being arranged in the same casing and in axial tandem alignment with the low pressure turbine driving the low pressure compressor; and the other one of said high pressure turbines being arranged in the same casing and in tandem axial alignment with the low pressure turbine providing the useful power output of the cycle.

The two high pressure compressors may be duplicates of one another, and likewise the two high pressure turbines may be duplicates of one another.

In order that the invention may be better understood and readily carried into effect, an embodiment thereof will now be described by way of example with reference to the accompanying drawing which is a diagrammatic sectional plan view of an embodiment of a plant according to the invention which comprises a low pressure axial flow compressor 1, an intercooler 2, two high pressure compressors 3, 4 in parallel flow connection, two combustion chambers 5, 6, two high pressure turbines 7, 8, two low pressure turbines 9, 10 and an alternator 11 forming the useful load arranged in the following manner: the low pressure compressor 1 has its driving flange on the inlet end of the low pressure compressor rotor (supplied by the air inlet duct 15) so that the delivery end of the compressor has a free shaft end, thus permitting the air to be delivered through an axially directed duct 21 leading im mediately from the end of the compressor annulus and discharging into an intercooler 2 placed closely adjacent to the delivery end of the low pressure compressor 1.

From this intercooler the cooled air is led through ducts 13, 14 to the inlets of the two high pressure air compressors 3, 4 which are arranged with their inlets at their free shaft ends and each is driven from its delivery end by one of the two high pressure turbines 7, 8 respectively.

Each of the two compressors 3, 4 delivers air to one of the two combustion chambers 5, 6 respectively, which in each case is mounted substantially directly on the compressor outlet flange thus avoiding the use of external ducting at this point. The hot gases leaving the outlet of each combustion chamber are directed into the inlet of the high pressure turbine 7, 8 respectively associated with its own compressor and, again, there is no external ducting because the turbine inlet is arranged at the driving end of the turbine 7, 8 respectively, that is, adjacent to the combustion chambers 5, 6.

Each of the two high pressure compressor-high pressure turbine units 3-7, 48, respectively, is arranged substantially in tandem axial alignment with one of the low pressure turbines 9, 10 respectively, and in such close proximity to it that the high pressure turbine 7, 8 respectively, may be contained in substantially the same outer casing as houses .its associated low pressure turbine 9, 10 respectively, so that the intermediate pressure gases leaving the blade annulus of the high pressure turbine may pass in an axial direction with the minimum of deflection or loss directly into the blade annulus of the low pressure turbine, from the outlet of which they emerge as exhaust gases and are led to atmosphere through exhaust ducts 19, 20 respectively.

One of the low pressure turbines, 9, is arranged in axial alignment with the low pressure compressor 1, a flange on the exhaust end of the turbine rotor being arranged in driving connection with the previously mentioned driving flange on the inlet end of the compressor rotor. The other low pressure turbine, 10, is arranged in axial alignment and in driving connection with an alternator 11 or other load unit in the normal fashion.

It will be appreciated that the complete installation thus consists of two independent sets which for convenience are preferably arranged side by side, the one parallel with the other. Each of the two sets consists of a number of units in axial alignment, the first set comprising-reciting the items in the order from the right hand end of the drawing: an intercooler 2, a low pressure compressor 1, a low pressure turbine 9 in driving connection with said compressor, a high pressure turbine 7 not in driving connection with the previously recited items but in driving connection with the next following item which is a high pressure compressor 3. The second set consists of an alternator 11 or other load unit in driving connection with a low pressure turbine 10, a high pressure turbine 8 not in driving connection with the previously recited items but in driving connection with the next following item which is a high pressure compressor 4. In the case of each set there is a combustion chamber 5, 6 respectively, mounted between the outlet of the high pressure compressor 3, 4 respectively, and the inlet of the high pressure turbine 7, 8 respectively. The ducting 13, 14 is provided for conveying cooled compressed air from the intercooler 2 to the inlets to the high pressure compressors 3, 4.

While in the embodiment as described hereinabove a single combustion chamber has been shown for each high pressure set (high pressure compressor, combustion chamber, fuel injection equipment, high pressure compressor and accessories), more than one combustion chamber can be used for each such set.

Preferably the whole gas flow leaving each of the high pressure turbines passes through the low pressure turbine arranged in alignment with it. However, a duct or ducts 18 suitable for conveying hot gases under pressure may be provided to connect the two sets, these ducts in each case forming a flow connection between the outlet from one high pressure turbine '7, 8 respectively, and the inlet to the other low pressure turbine 10, 9 respectively, their purpose being to provide the balancing fiow of gas necessary in those cases in which, although the two high pressure compressors 3, 4 and two high pressure turbines 7, 8 are each duplicates one of the other and thus pass substantially the same mass flow of gas, the two low pressure turbines 9, 10 differ in size, one from the other, and are not designed to have the same mass flow of gas passing through each.

A balancing duct 16 connecting the outlets of the two high pressure compressors 3, 4 with one another may be provided.

A blow-off duct 12 from the intercooler 2 may be connected through valve means 17 directly with the air inlet duct to the low pressure compressor 1.

While in the embodiment as described hereinabove the two high pressure sets are, as stated, preferably duplicates of one another, they may have the heights of their blades adjusted to suit different mass flow required by the low pressure turbines associated with them.

We claim as our invention:

1. A compound gas turbine power plant comprising in combination two high pressure compressors in parallel flow arrangement relative to one another, two high pressure gas turbines and two combustion chambers, each of the said high pressure turbines driving directly one of the said high pressure compressors and receiving compressed m0- tive fluid therefrom through the said combustion chamber, each of the said two high pressure turbines and associated high pressure compressors being journalled independently of the other, two low pressure gas turbines each arranged directly in alignment and series flow connection with one of the said high pressure turbines but journalled for inde pendent rotation, a low pressure compressor in alignment with and directly driven by one of the said low pressure turbines, and an intercooler directly connected with the discharge end of the said low pressure compressor and connected in parallel to the said two high pressure compressors, the other one of the said low pressure ttubines driving the useful load.

2. A gas turbine plant as claimed in claim 1 wherein the discharge of each high pressure turbine is in direct fluid communication with the entry of its associated low pressure turbine, and substantially the whole gases discharged from each high pressure turbine pass through the asosciated low pressure turbine.

3. A gas turbine plant as claimed in claim 1 wherein the said high pressure compressors are substantially duplicates of one another.

4. A gas turbine plant as claimed in claim 1 wherein the said high pressure turbines are substantially duplicates of one another.

5. A gas turbine plant as claimed in claim 1 wherein the two sub-combinations each comprising a high pressure compressor, a combustion chamber and a high pressure turbine are substantially duplicates of one another.

6. A compound gas turbine power plant comprising in combination one set including a high pressure compressor, a high pressure turbine in direct driving connection with the said high pressure compressor, a combustion chamber directly connected between the said high pressure compressor and the said high pressure turbine, a low pressure turbine arranged in alignment and in direct series flow connection with the said high pressure turbine but journalled independently therefrom and driving the useful load, a second set including a high pressure compressor, a high pressure turbine in direct driving connection with this last mentioned high pressure compressor, a combustion chamber directly connected between the said last mentioned high pressure compressor and the said last mentioned high pressure turbine, a low pressure turbine arranged in alignment and in direct series flow connection with the said last mentioned high pressure turbine, a low pressure compressor in alignment and in direct driving connection with the said last mentioned low pressure turbine, and together With the latter being journalled independently of the said last mentioned high pressure turbine and high pressure compressor, the said two sets being arranged side by side with parallel center lines, an intercooler arranged in alignment and in direct fluid communication with the said low pressure compressor which discharges directly into it, and ducts connecting the said intercooler in parallel flow connection to each of the said two high pressure compressors.

7. A compound gas turbine power plant comprising in combination two high pressure compressors, two high pressure gas turbines and two combustion chambers, two common casings, each of the said high pressure turbines directly driving one of the said high pressure compressors and being journalled together with it in one of the said casings independently of the said other turbine and compressor, each of the said combustion chambers being directly connected to the discharge end of one of the said high pressure compressors and to the intake of the associated high pressure turbine on the said common casing thereof, two low pressure turbines, each journalled in alignment with one of the said high pressure turbines in the common casing thereof for independent rotation, the motive gases from the high pressure turbine passing inside the said casing into the said low pressure turbine, a low pressure compressor in alignment with and directly driven by one of the said low pressure turbines, and an intercooler directly connected with the discharge end of the said low pressure compressor and connected in parallel to the said two high pressure compressors, the other one of the said low pressure turbines driving the useful load.

8. A compound gas turbine power plant comprising in combination two high pressure compressors, two high pressure gas turbines and two combustion chambers, each of the said high pressure turbines driving directly one of the said high pressure compressors and receiving compressed motive fluid therefrom through the said combustion chamber, each of the said two high pressure turbines and associated high pressure compressors being journalled independently of the other, two low pressure gas turbines each arranged directly in alignment and series flow connection with one of the said high pressure turbines but journalled for independent rotation, a low pressure axial flow compressor coupled at its entrance side directly to one of the said low pressure gas turbines, and an intercooler arranged in alignment with the said low pressure compressor dirscharging axially directly into the said intercooler, the latter being connected in parallel to the said two high pressure compressors, the other one of the said low pressure turbine driving the useful load.

9. A compound gas turbine power plant comprising in combination two high pressure compressors, two high pressure gas turbines and two combustion chambers, each of the said high pressure turbines driving directly one of the said high pressure compressors and receiving compressed motive fluid therefrom through the said combustion chamber, each of the said two high pressure turbines and associated high pressure compressors being journalled independently of the other, two low pressure gas turbines each arranged directly in alignment and series flow connection With one of the said high pressure turbines but journalled for independent rotation, a low pressure compressor in alignment with and directly driven by one of the said low pressure turbines, an intercooler directly connected with the discharge end of the said low pressure compressor and connected in parallel to the said two high pressure compressors, the other one of the said low pressure turbines driving the useful load, and a balancing duct connecting the discharge ends of the said two high pressure compressors.

10. A compound gas turbine power plant comprising in combination two high pressure compressors, two high pressure gas turbines and two combustion chambers, each of the said high pressure turbines driving directly one of the said high pressure compressors and receiving compressed motive fluid therefrom through the said combustion chamber, each of the said two high pressure turbines and associated high pressure compressors being journalled independently of the other, two low pressure gas turbines each arranged directly in alignment and series flow connection with one of the said high pressure turbines but journalled for independent rotation, a low pressure compressor in alignment with and directly driven by one of the said low pressure turbines, an intercooler directly connected with the discharge end of the said low pressure compressor and connected in parallel to the said two high pressure compressors, the other one of the said low pressure turbines driving the useful load and a duct connecting the discharge end of one high pressure turbine to the inlet of the low pressure turbine which is in direct series flow arrangement with the other high pressure turbine.

References Cited in the file of this patent UNITED STATES PATENTS 2,372,686 Sdille Apr. 3, 1945 2,477,184 Imbert July 26, 1949 2,547,660 Prince Apr. 3, 1951 2,601,194 Whittle June 17, 1952 FOREIGN PATENTS 254,065 Switzerland Dec. 1, 1948 724,471 Germany Aug. 27, 1942 

